[RFA] Fix Ada memory corruption

[RFA] Fix Ada memory corruption

[Keith Seitz]

[-- Attachment #1: Type: text/plain, Size: 395 bytes --]

Hi,

Tom's recent symbol_set_names patch exposed this Ada bug, which results 
in memory corruption while computing an alternate symbol name.

This fixes the crash I was seeing in gdb.ada/interface.exp tests.

Ok?

Keith

ChangeLog
2009-11-19  Keith Seitz  <keiths@redhat.com>

	* ada-lang.c (find_old_style_renaming_symbol): Change
	function_name to const and use strncpy to stript the
	suffix.

[-- Attachment #2: ada-mem-err.patch --]
[-- Type: text/plain, Size: 2037 bytes --]

Index: ada-lang.c
===================================================================
RCS file: /cvs/src/src/gdb/ada-lang.c,v
retrieving revision 1.229
diff -u -p -r1.229 ada-lang.c
--- ada-lang.c	2 Jul 2009 17:25:52 -0000	1.229
+++ ada-lang.c	19 Nov 2009 18:51:42 -0000
@@ -6505,7 +6505,7 @@ find_old_style_renaming_symbol (const ch
          qualified.  This means we need to prepend the function name
          as well as adding the ``___XR'' suffix to build the name of
          the associated renaming symbol.  */
-      char *function_name = SYMBOL_LINKAGE_NAME (function_sym);
+      const char *function_name = SYMBOL_LINKAGE_NAME (function_sym);
       /* Function names sometimes contain suffixes used
          for instance to qualify nested subprograms.  When building
          the XR type name, we need to make sure that this suffix is
@@ -6514,9 +6514,11 @@ find_old_style_renaming_symbol (const ch
       const int function_name_len = ada_name_prefix_len (function_name);
       const int rename_len = function_name_len + 2      /*  "__" */
         + strlen (name) + 6 /* "___XR\0" */ ;
+      int bufsize = rename_len * sizeof (char);
 
       /* Strip the suffix if necessary.  */
-      function_name[function_name_len] = '\0';
+      int end = (strlen (function_name) > function_name_len
+		 ? function_name_len : strlen (function_name));
 
       /* Library-level functions are a special case, as GNAT adds
          a ``_ada_'' prefix to the function name to avoid namespace
@@ -6526,9 +6528,10 @@ find_old_style_renaming_symbol (const ch
           && strstr (function_name, "_ada_") == function_name)
         function_name = function_name + 5;
 
-      rename = (char *) alloca (rename_len * sizeof (char));
-      xsnprintf (rename, rename_len * sizeof (char), "%s__%s___XR", 
-		 function_name, name);
+      rename = (char *) alloca (bufsize);
+      gdb_assert (end < bufsize);
+      strncpy (rename, function_name, end);
+      xsnprintf (rename, bufsize - end, "__%s___XR", name);
     }
   else
     {

Re: [RFA] Fix Ada memory corruption

[Joel Brobecker]

> ChangeLog
> 2009-11-19  Keith Seitz  <keiths@redhat.com>
>
> 	* ada-lang.c (find_old_style_renaming_symbol): Change
> 	function_name to const and use strncpy to stript the
> 	suffix.

Gah! I was just working on this yesterday evening.  I haven't finished,
but while I'm at it, I'm merging it with some local changes.  I'll see
if I can apply your change on top of mine, and then commit.

Thanks for the patch!

-- 
Joel

Re: [RFA] Fix Ada memory corruption

[Joel Brobecker]

[-- Attachment #1: Type: text/plain, Size: 560 bytes --]

> > 	* ada-lang.c (find_old_style_renaming_symbol): Change
> > 	function_name to const and use strncpy to stript the
> > 	suffix.

I think there was a mistake in the last part of the patch and you would
have ended up overwriting the function name with the __<var-name>___XR
portion.

I was almost done with my own version of the change, so I finished it,
tested it, and checked it in.

While working on this, I also added handling for various suffixes
that get introduced for nested/static procedures as well as special
routines (Protected Objects).

-- 
Joel

[-- Attachment #2: 0001-Fix-memory-corruption-during-old-style-renamings-pro.patch --]
[-- Type: text/x-diff, Size: 2842 bytes --]


gdb/
    * ada-lang.c (ada_remove_Xbn_suffix): New function.
    (find_old_style_renaming_symbol): Add handling for function suffixes
    present in the name of various procedures.
    Do not overwrite the function symbol's name.
---
 gdb/ada-lang.c |   36 +++++++++++++++++++++++++++++++-----
 1 files changed, 31 insertions(+), 5 deletions(-)

diff --git a/gdb/ada-lang.c b/gdb/ada-lang.c
index b5590f7..3c9ab77 100644
--- a/gdb/ada-lang.c
+++ b/gdb/ada-lang.c
@@ -873,6 +873,26 @@ ada_remove_po_subprogram_suffix (const char *encoded, int *len)
     *len = *len - 1;
 }
 
+/* Remove trailing X[bn]* suffixes (indicating names in package bodies).  */
+
+static void
+ada_remove_Xbn_suffix (const char *encoded, int *len)
+{
+  int i = *len - 1;
+
+  while (i > 0 && (encoded[i] == 'b' || encoded[i] == 'n'))
+    i--;
+
+  if (encoded[i] != 'X')
+    return;
+
+  if (i == 0)
+    return;
+
+  if (isalnum (encoded[i-1]))
+    *len = i;
+}
+
 /* If ENCODED follows the GNAT entity encoding conventions, then return
    the decoded form of ENCODED.  Otherwise, return "<%s>" where "%s" is
    replaced by ENCODED.
@@ -6514,12 +6534,14 @@ find_old_style_renaming_symbol (const char *name, struct block *block)
          the XR type name, we need to make sure that this suffix is
          not included.  So do not include any suffix in the function
          name length below.  */
-      const int function_name_len = ada_name_prefix_len (function_name);
+      int function_name_len = ada_name_prefix_len (function_name);
       const int rename_len = function_name_len + 2      /*  "__" */
         + strlen (name) + 6 /* "___XR\0" */ ;
 
       /* Strip the suffix if necessary.  */
-      function_name[function_name_len] = '\0';
+      ada_remove_trailing_digits (function_name, &function_name_len);
+      ada_remove_po_subprogram_suffix (function_name, &function_name_len);
+      ada_remove_Xbn_suffix (function_name, &function_name_len);
 
       /* Library-level functions are a special case, as GNAT adds
          a ``_ada_'' prefix to the function name to avoid namespace
@@ -6527,11 +6549,15 @@ find_old_style_renaming_symbol (const char *name, struct block *block)
          have this prefix, so we need to skip this prefix if present.  */
       if (function_name_len > 5 /* "_ada_" */
           && strstr (function_name, "_ada_") == function_name)
-        function_name = function_name + 5;
+        {
+	  function_name += 5;
+	  function_name_len -= 5;
+        }
 
       rename = (char *) alloca (rename_len * sizeof (char));
-      xsnprintf (rename, rename_len * sizeof (char), "%s__%s___XR", 
-		 function_name, name);
+      strncpy (rename, function_name, function_name_len);
+      xsnprintf (rename + function_name_len, rename_len - function_name_len,
+		 "__%s___XR", name);
     }
   else
     {
-- 
1.6.0.4